The invention relates to hinge joints which can be utilized in seats, particularly in the seats of vehicles including motor vehicles. Still more particularly, the invention relates to improvements in hinge joints which can be utilized in seats for any one of a number of different purposes including (a) pivotably connecting the back rest to the body supporting portion of a seat, (b) vertically adjustably mounting the body supporting portion, (c) tiltably mounting the body supporting portion, (d) adjustably mounting an arm rest, (e) reciprocably mounting the body supporting portion, (f) adjustably mounting a lateral portion, (g) adjustably mounting a hip supporting portion, (h) adjustably mounting a head rest or shoulder rest and/or (i) effecting simultaneous adjustments of two or more mobile parts relative to one or more stationary parts in a seat.
It is already known to provide the seat of a motor vehicle (e.g., a driver's seat and/or a seat next to the driver's seat) with a stationary component which is affixed to the frame of a vehicle and/or to the body supporting portion of the seat, with a second component which is affixed to a movable part, such as the pivotable back rest of the seat, a pintle which connects the second component to the first component for pivotal movement about a fixed axis (e.g., a horizontal axis), and a mechanism which can be actuated to adjust the second component relative to the first component and automatically locks or otherwise holds the second component in a newly selected position relative to the first component. Reference may be had, for example, to German Pat. No. 30 13 304 C2 which further discloses two substantially wedge-shaped arcuate sections partially surrounding the pintle and being biased apart by a spring which simultaneously urges the sections against a motion transmitting member. An antifriction bearing is installed between the first component and the arcuate sections. The German patent further discloses that the second section can be turned on a centric (i.e., non-eccentric) portion of the pintle. The arcuate sections cooperate with the adjacent portion of the pintle to constitute an eccentric for the first component of the patented hinge joint. The wedge-like sections cooperate with the spring to automatically establish a certain clearance when the adjusting mechanism is actuated to change the position of the second component relative to the first component, and such clearance is reduced to zero when the adjusting operation is completed. The establishment of a clearance is desirable and advantageous because it contributes to the convenience of adjustment. Nevertheless, each adjustment involves the application of a force which must suffice to overcome sliding friction between the arcuate sections and the adjacent part or parts as well as sliding friction between the pintle and one or more neighboring parts. It has been found that a person wishing to adjust the second component relative to the first component must overcome a rather pronounced initial resistance to movement of the second component relative to the first component as well as a rather pronounced resistance of the second component to continuation of its movement relative to the first component.
Commonly owned U.S. Pat. No. 5,154,475 granted Oct. 13, 1992 to Egon Kafitz for "Hinge joint for the seats of motor vehicles and the like" discloses a hinge joint wherein the eccentric between the pintle and one of the components further includes a centering element which extends between the narrower end portions of the wedge-like sections. When a coil spring between the wider end portions of the wedge-like sections is free to move such wider end portions away from each other, the sections act as a means for blocking the second component of the hinge joint against movement from a newly selected position. The bias of the spring must be overcome in order to adjust the angular position of the second component relative to the first component of the patented hinge joint. The centering element can constitute a sleeve which is surrounded by the wedge-like sections and includes a portion which is received with angular play between the narrower end portions of the wedge-like sections. The concave surfaces of the sections are in frictional sliding contact with the external surface of the sleeve. Kafitz further proposes to employ a ball bearing or a roller bearing which is installed between the sleeve and one of the two components of the patented hinge joint. In spite of the provision of a bearing, the adjustment of the hinge joint of Kafitz still necessitates the application of a relatively large initial force in order to set the second component in motion relative to the first component, namely to disengage the wedge-like sections from the adjacent surface or surfaces.
A further known proposal involves the utilization of a cupped entraining member which is partially surrounded by the wedge-like sections of the eccentric. The entraining member contains an antifriction bearing for the second component of the thus modified hinge joint. The first component surrounds the wedge-like sections. Such mounting reduces the friction between relatively movable parts when the hinge joint is to be actuated to adjust the position of the second component relative to the first component. However, the reduction of friction is not pronounced so that each and every adjustment still necessitates the application of a rather substantial force, not only to overcome the initial resistance to adjustment but also to maintain the second component in motion until such component reaches a desired new position relative to the first component.